Hard floor surface cleaner utilizing an aerated cleaning liquid

ABSTRACT

A method of cleaning a hard floor surface with a surface maintenance vehicle including the steps of generating a foam-like aerated cleaning liquid, selectively conveying the foam-like aerated cleaning liquid to the hard floor surface and a scrubbing medium operatively coupled to the surface maintenance vehicle, scrubbing the hard floor surface with said rotating scrubbing medium and said foam-like aerated cleaning liquid so as to loosen soil from the hard floor surface leaving behind a soiled solution of cleaning liquid and soil, and removing at least a portion of the soiled solution from the hard floor surface through a fluid recovery device. Additional aspects of the present invention include devices for performing the cleaning method.

RELATED APPLICATION

[0001] This application hereby incorporates by reference and, under 35U.S.C. § 119(e), claims the benefit of priority of U.S. ProvisionalPatent Application Ser. No. 60/308,773 filed Jul. 30, 2001.

FIELD OF THE INVENTION

[0002] The present invention relates generally to surface maintenance orconditioning machines, and more particularly to those machines employingone or more surface maintenance or conditioning appliances or tools toperform a hard floor surface wet scrubbing task.

BACKGROUND OF THE INVENTION

[0003] Hard floor surface scrubbing machines are widely used to cleanthe floors of industrial and commercial buildings. They range in sizefrom a small model which may clean a path ranging from 15 inches up to36 inches wide controlled by an operator walking behind it, to a largemodel cleaning a path as wide as five feet controlled by an operatorriding on the machine. Such machines in general are wheeled vehicleswith suitable operator controls. Their bodies contain power and drivemeans, a solution tank to hold a cleaning liquid and a recovery tank tohold soiled solution recovered from the floor being scrubbed. Thecleaning liquid may be water and a chemical detergent. The detergenttypically includes a solvent, builder, and surfactant. Builders andsurfactants provide for foam generation and foam stability. A scrub headwhich contains one or more scrubbing brushes and associated drive meansare attached to the vehicle and may be located in front of, under orbehind it. A solution distribution system dispenses cleaning liquid fromthe solution tank to the floor in the vicinity of the scrubbing brush orbrushes. For a typical scrubber with a 32 inch wide scrub swath, thesolution distribution rate varies between 0.5 gallons per minute (GPM)to 1.0 GPM.

[0004] Hard floor surface scrubbing machines typically further include asystem to recover soiled scrubbing solution from the floor after it hasbeen scrubbed. A solution recovery system may be a vacuum systemincluding, for example, a double lipped vacuumized squeegee that wipesthe floor behind the scrub head and collects the soiled scrubbingsolution of water, detergent and soilage that has been loosened from thefloor. The soiled scrubbing solution may include foam or froth generatedby mechanical action of the brushes against the cleaning solution andthe hard floor surface. Additional amounts of foam may be generatedthrough the vacuum recovery process. Foam (air expanded cleaningsolution) has heretofore been a shortcoming of prior art scrubbers asfoam occupies a significantly greater volume as compared to the volumeof unexpanded cleaning solution. Excessive foam within the recovery tankcan necessitate shutting down the machine and emptying the recovery tankbefore the solution tank is empty, which reduces the productivity of themachine. As a result, foam elimination or reduction techniques haveincluded specifically adapted enlarged solution recovery tanks and theaddition of defoaming chemicals to the recovered solution tank.

[0005] Other limitations of vacuum systems for soiled solution recoveryinclude power requirements, noise generation, and reliability. Analternative to vacuum-based soiled solution recovery systems for useupon a hard floor surface scrubbing machine would be desired.

[0006] One limitation of prior art scrubbers has been a relativelylimited operational run time. For a typical scrubber with a 32 inch widescrub swath and 30 gallon solution tank, the solution distribution ratevaries between 0.5 GPM to 1.0 GPM. Run time based on solution capacityis between approximately 30 to 40 minutes. Merely increasing the size ofthe cleaning solution tanks is not a viable solution to achievingincreased machine run times. An increase in cleaning solution capacitytypically necessitates modifications to the frame and motive components,all of which result in additional weight and energy requirements forsuch a device. To the contrary, a need exists for a device having anincreased run time achieved by reducing the amount of water required forthe scrubbing process.

[0007] Another aspect of prior art scrubbers is the inefficient use ofcleaning liquid in the scrub process. A relatively large amount ofcleaning liquid is utilized to ensure wetting of the floor surface. Thescrub process generates a relatively large amount of soiled cleaningliquid, most of which is recovered by the scrubber. Disposal of soiledsolution in some applications remains an issue, especially where thecleaning process removes harmful or hazardous chemicals. Specialhandling or additional costs may be incurred to properly dispose aparticularly soiled solution. By reducing the amount of water needed toperform a scrubbing process, a concomitant reduction in the amount ofsoiled solution is achieved. A need exists for a cleaning processproviding efficient usage of cleaning solution.

[0008] The prior art discloses devices for cleaning surfaces, namelycarpets, utilizing foam generation systems and mechanical brushes. Thesedevices have utilized a variety of foam generation systems and recoverysystems. Examples of such foam cleaning devices include U.S. Pat. Nos.3,761,987; 3,931,662; and 5,813,086.

[0009] Nayfa et al (U.S. Pat. Nos. 3,761,987 and 3,931,662) discloses amachine for scrubbing or shampooing rugs or carpeted floor surfaces, forscrubbing hard floor surfaces, or for waxing and polishing hard floorsurfaces. Stated objects of the invention of Nayfa et al. include:

[0010] an improved floor surface cleaning machine having the capabilityto shampoo and remove surface dirt from a carpet surface in oneoperation, to scrub and remove surface dirt from a hard floor surface inone operation, or to apply wax to and polish a floor surface in oneoperation,

[0011] a floor surface cleaning machine having a cleaning solutionfoaming system within the machine and a pressurized foam dispensingsystem,

[0012] a rug cleaning machine having means for scrubbing the pile,removing the dirt from the pile, and lifting the pile to originalposition in one operation,

[0013] a rug cleaning machine wherein the machine support and driverollers function as squeegies to direct the cleaning foam and entrappeddirt toward the vacuum pickup nozzles, and

[0014] a floor surface cleaning machine having an improved solutiondispensing mechanism including means for forming a foam, means foreffecting flow of the foam under pressure, and means for controlling therate of flow of foam to the floor surface.

[0015] These devices have not addressed limitations of prior art floorscrubbers, such as efficient cleaning solution usage in a hard floorsurface scrubbing process.

SUMMARY AND OBJECTS OF THE INVENTION

[0016] Briefly stated, an improved hard floor surface scrubbing machineaccording to the present invention includes an aerator for generating afoam-like aerated cleaning liquid, one or more scrub brushes forengaging aerated cleaning liquid and the hard floor surface, and asoiled solution recovery system for removing soiled solution from thehard floor surface. A variety of liquid aerators may be utilized topractice the present invention. A particularly preferred aeratorincludes a pressurized air source, a pressurized cleaning liquid source,and a plurality of mixing elements for generating the aerated cleaningliquid. Alternative soiled solution recovery systems may be utilized inembodiments of the present invention.

[0017] An object of the present invention is to overcome the drawbacksof the conventional technology and to provide an efficient hard floorsurface scrubbing machine.

[0018] Another object of the present invention is to provide a hardfloor surface scrubbing machine which utilizes a foam-like aeratedcleaning liquid in an efficient scrubbing process. The cleaning liquidmay be water and a chemical surfactant. The aerated cleaning liquid maybe generated via a variety of known aeration devices or systems. Theaerated cleaning liquid permits a substantial reduction in the amount ofcleaning solution liquid required in a scrub cleaning process. Thereduction of cleaning liquid requirements may translate into decreasedmachine size and/or increased machine run times. Additionally, theamount of soiled cleaning solution which may require special disposal oradditional handling may be reduced.

[0019] An aspect of the present invention is the provision of a cleaningliquid which can be efficiently aerated via known aeration devices,applied to a surface during a scrubbing process, and be rapidly dearatedprior to a soiled solution recovery process.

[0020] Another aspect of the present invention is the provision of acleaning liquid which may be efficiently aerated to a foam-likeconsistency, applied to the floor surface, and quickly dearated byengagement with a scrub brush. In a preferred embodiment of the presentinvention, the foam-like aerated cleaning liquid is substantiallydearated by the scrub brush prior to soiled solution recovery.

[0021] Another aspect of the present invention is the provision of adefoaming device for de-aerated foamed soiled solution recovered duringmachine operation. The defoaming device may include a chemical-baseddefoamant, or may include a radiant heating element to thermallyde-aerate the recovered foam.

[0022] Another aspect of the present invention is to provide a chemicaldosing or metering system for combining a chemical with water to createa cleaning liquid during operation of the machine. In one embodiment ofthe invention, a machine may have a clean water tank and a chemicaldosing system for combining water and a chemical prior to aeration. Thechemical dosing system may include a configured removable chemicalcartridge adapted to engage a correspondingly configured portion of thecleaning machine. The chemical dosing system may include active orpassive elements for combining a chemical with water to create thecleaning liquid.

[0023] Yet another aspect of the present invention is a process forcleaning hard floor surfaces including the steps of aerating a cleaningliquid to form an aerated cleaning liquid, selectively conveying theaerated cleaning liquid to the hard floor surface and a rotating scrubbrush, engaging the hard floor surface and the aerated cleaning liquidwith the rotating scrub brush to loosen soil from the hard floor surfaceand to create a soiled solution of cleaning liquid and soil, andremoving at least a portion of the soiled solution from the hard floorsurface through the fluid recovery system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a side elevation view of the scrubber of the presentinvention.

[0025]FIG. 2 is a front elevation view of the scrubber of FIG. 1.

[0026]FIG. 3 is a detailed front elevation view of a cleaning liquidaeration system according to the present invention.

[0027]FIG. 4 is a detailed front elevation view of a portion of ascrubber according to the present invention.

[0028]FIG. 5 is a side elevation view of another embodiment of ascrubber of the present invention.

[0029]FIG. 6 is a cross sectional view of yet another embodiment of ascrubber similar to that of FIGS. 1-4.

[0030]FIG. 7 is a detailed front elevation view of another embodiment ofa cleaning liquid aeration system according to the present invention.

[0031]FIG. 8 is a detailed front elevation view of another embodiment ofa cleaning liquid aeration system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032]FIG. 1 illustrates an embodiment of a surface maintenance vehicleaccording to the present invention. The illustrated surface maintenancevehicle is a walk-behind scrubber machine 10 utilized to clean hardfloor surfaces, such as concrete, tile, vinyl, terrazzo, etc. Inalternative embodiments, the surface maintenance vehicle may be aride-on or towed-behind vehicle performing a scrubbing operation asdescribed herein. The surface maintenance vehicle may be powered throughan on-board power source, such as batteries or an IC engine, or thoughan electrical cord. In the embodiment of FIG. 1, the scrubber 10includes a recovery tank 12, a lid 14 and a front cover 16. The lid 14is attached along one side of the recovery tank by hinges (not shown) sothe lid 14 can be pivoted up to provide access to the interior of thetank 12. The lid 14 defines a cleaning solution tank 18 for containing acleaning liquid, such as a mixture of water and a cleaning chemical tobe conditioned, applied to the hard floor surface, and recovered fromthe floor surface as further described herein.

[0033] A scrub head 20 includes a scrubbing medium 22, shrouds 24, and ascrubbing medium drive 26. The scrubbing medium 22 may be one or morebrushes. In the illustrated embodiment, a pair of brushes 22 define thescrubbing medium. The brushes 22 may include bristle brushes, padscrubbers, or other hard floor surface engaging devices for scrubbing.The term “brush” as used herein is not limited to bristle devices, butis intended to cover a variety of known hard floor surface scrubbingelements. One or more electric motor brush drives 26 may be utilized torotate the brushes 22. The scrubbing medium may be a disk-type scrubbrush rotating about a generally vertical axis of rotation relative tothe hard floor surface. The scrubbing medium may also be acylindrical-type scrub brush rotating about a generally horizontal axisof rotation relative to the hard floor surface. Alternative embodimentsof the present invention may include scrub brushes 22 being oscillatedrather than rotated into contact with the hard floor surface. A varietyof brush rotation and/or oscillation devices would be appreciated bythose skilled in the relevant arts. In the illustrated embodiment, apair of rotating disk brushes 22 are utilized. The scrub head 20 isattached to the machine 10 such that the scrub head 20 can be movedbetween a lowered working position and a raised traveling position.

[0034] A machine frame supports the recovery tank 18 on wheels 24 andcasters 26. Further details of the frame are shown and described in U.S.Pat. No. 5,611,105 the disclosure of which is incorporated herein byreference. Wheels 24 are preferably driven by a motor and transaxleassembly shown schematically at 28. The rear of the frame carries alinkage 30 to which a fluid recovery device 32 is attached. In theembodiment of FIG. 2, the fluid recovery device 32 includes a vacuumsqueegee 34 in vacuum communication with an inlet chamber in therecovery tank 12 through a hose 36. The bottom of the inlet chamber isprovided with a drain 40 with a drain hose 42 connected to it. Analternative non-vacuumized fluid recovery device 32 is described in moredetail herein with particular reference to FIG. 5.

[0035] The vehicle body incorporates a battery compartment 44 in whichbatteries 46 reside. The batteries 46 provide power to the drive motors26, scrub head 20, and a vacuum fan 48. The vacuum fan 48 is mounted inthe lid 14. A control unit 50 mounted on the rear of the body includessteering control handles 52 and the necessary operating controls andgauges for the scrubber. Additional aspects of automatic scrubbermachines are disclosed in U.S. Pat. Nos. 5,483,718; 5,515,568; and5,566,422, each incorporated by reference herein. Alternative motivesystems such as an IC engine system may be utilized in anotherembodiment of the present invention.

[0036] In a preferred embodiment of the present invention the cleaningliquid includes water and a chemical surfactant. Alternative cleaningliquids may also be utilized in other embodiments of the presentinvention. Alternative cleaning liquids may be water or chemical based.Alternative cleaning liquids may include one or more surfactants,builders, solvents, or other components. A particularly preferredsurfactant is DeTERIC CP-Na-38 manufactured by DeForest Enterprises,Inc. of Boca Raton, Fla. A particularly preferred surfactantconcentration of the cleaning liquid is approximately 0.1%. In apreferred embodiment, no additional solvents or builders are utilized.As described in more detail hereinafter, the cleaning liquid is aeratedto create a foam/water mix which is delivered to the hard floor surfaceand utilized in a scrubbing process. The foam-like aerated cleaningliquid facilitates an efficient wetting of the floor surface. Asdescribed in more detail herein, one benefit of the preferred surfactantis the ability to efficiently aerate the cleaning liquid into a foam,apply the foamed cleaning liquid to the hard floor surface, work thefoamed cleaning liquid with the scrub brushes, and substantiallydeaerate the foamed cleaning liquid prior to soiled solution recover. Inoperation, dearation of the aerated cleaning liquid is rapidly achievedvia brush 22 contact. As a result, relatively little foam is transferredinto the recovery tank 12. One skilled in the relevant arts willappreciate that alternative surfactants may also be practicable. As aresult, the identification of a particular surfactant herein is notintended to be limiting. Additionally, detergents including a surfactantalong with other solvents, builders, or other components may bepracticable for an application of the present invention.

[0037] The cleaning liquid may be contained within solution tank 18 as amixture of water and the surfactant. The surfactant may be added towater within the solution tank 18 to achieve a predeterminedconcentration within the solution tank 18. For example, a predeterminedamount of surfactant may be added to a predetermined amount of water,such as during a refilling operation. Alternatively, the mixture ofwater and surfactant may be achieved during machine operation through achemical dispenser. Additional aspects of such dispensers are describedhereinafter with reference to FIG. 7 and FIG. 8.

[0038] Referring to FIGS. 1-4, a cleaning liquid aerator for generatinga foam-like aerated cleaning liquid for application to the hard floorsurface during a scrubbing process according to the present invention isgenerally indicated at 60. The aerator 60 may include a variety of knownfoam generation devices, including but not limited to pressurized airand/or pressurized liquid systems, agitation systems, etc. Aparticularly preferred aerator 60 is disposed on the housing above thescrubbing head 20 and includes an air system 62 for pressurizing air, aliquid cleaning solution system 64 for pressurizing cleaning liquid, afirst mixing element 66 for receiving pressurized air and pressurizedliquid cleaning solution, a second mixing element 68 for further mixingin fluid communication with the first mixing element 66. A foamdispensing system 70 distributes foam generated by the mixing elements66, 68. An electric solenoid valve 72 is provided to control the flow offoam from the aerator 60.

[0039] Referring particularly to FIG. 3, additional aspects of thecleaning liquid aerator 60 will be described. The air system 62 forgenerating and conveying pressurized air includes an air pump 74, acheck valve 76, and associated fluid conduits 78, 80. In a particularlypreferred embodiment of the machine, the air pump is a piston pump modelnumber 22D1180-206-1002 manufactured by Gast Manufacturing, Inc., ofBenton Harbor, Mich. Other types of air pumps may also be practicable inalternative foam systems, including but not limited to different piston,diaphragm or rotary vane pumps. Check valve 76 is provided for back flowprevention of cleaning solution into the air pump 74. A measuredpressure at the air pump output during operation is approximately 40pounds per square inch (psi).

[0040] The system for generating and conveying pressurized cleaningliquid includes a diaphragm pump 82, a metering orifice 84, andassociated fluid conduits 86, 88, 90. The diaphragm pump 82 receivescleaning liquid from tank 18 via conduit 86. In a particularly preferredembodiment of the machine, the diaphragm pump is model number8006-543-250 manufactured by Shur Flo, of Garden Grove, Calif. Pump 82output is conducted via conduit 88 to metering orifice 84. In onepreferred embodiment, metering orifice 84 size is 0.0030 inch. Flow ratethrough the metering orifice 84 during operation is approximately 0.2gallons per minute. Output from metering orifice 84 is conducted to thefirst mixing element 66 via conduit 90.

[0041] The first mixing element 66 receives pressurized air from the airpump 74 via conduit 80 and pressurized cleaning solution from thesolution pump 82 via conduit 90 and discharges a mixture of pressurizedair and cleaning liquid through an outlet port 98. The first mixingelement 66, in this embodiment a Y coupling, has a pair of inlet ports94, 96 and an outlet port 98 through which the mixture is discharged.First mixing element 66 may be alternatively configured, though definingat least a pair of inlet ports for pressurized air and pressurizedcleaning liquid and an outlet port for the mixture. First mixing element66 may be defined as a passive mixing element. An alternative firstmixing element may include active mixing devices, such as energizedimpeller.

[0042] The outlet port 98 of the first mixing element 66 is coupled tothe electric solenoid valve 72 via conduit 92. Valve 72 controls theflow of mixture to the second mixing element 68 via conduit 100. Valve72 is operable between an open position in which solution is permittedto flow out of the first mixing element 66 and a closed position inwhich solution flow is blocked. Alternative valves may be used tocontrol the flow of mixture within the system, including but not limitedto variable output valves, etc.

[0043] The second mixing element 68 receives and further mixes thepressurized air and cleaning liquid from the first mixing element 66.Second mixing element 68 is a passive element including a relativelyrigid receiver 102 having an inlet port 104 and an outlet port 106. Adiffusion medium 108 is contained within the receiver 102. The diffusionmedium 108 is capable of producing foam by shearing action, airentrainment or a combination of both. In a preferred embodiment, thediffusion medium 108 includes a plurality of SCOTCH-BRITE brand copperpads, manufactured by Minnesota Mining and Manufacturing Company of St.Paul, Minn. Alternative diffusion medium may also be practicable,including but not limited to glass beads, foams, and other poroussubstrates.

[0044] The length and diameter of the receiver 102 as well as structureof the diffusion medium 108, are sized so as to maintain the operatingpressure of the foaming system 60 at a desired level. For the embodimentof FIGS. 2-4, the operating pressure within air conduit 78 is about 40psi. The diffusion medium 108 and receiver 102 size affect the qualityof the foam generated in the second mixing element 68. Moreparticularly, using coarser diffusion medium 108 allows for easierpassage of the foam through the receiver 102 since there are fewercontact, or blocking, points between medium 108 in the receiver 102.However, the coarser diffusion medium also results in larger foambubbles. By using a sufficiently long receiver 102 with an appropriatediffusion medium 108, large foam bubbles formed near the upstream end ofthe receiver 102 will break down into more desirable smaller bubblesprior to reaching the downstream end of the receiver 102. As an example,the receiver 102 of the illustrated embodiment is about 9 inches longand has an inner diameter of approximately 2 inches. The receiver 102may be provided at an incline relative to the ground surface so thatinlet port 104 is at a slightly lower elevation than outlet port 106. Byso providing the inlet port 104 above the outlet port, the amount ofaerated cleaning liquid delivered to the scrub brushes 22 after thesolenoid valve 72 has closed may be minimized. Various modifications andadaptations to the aerator 60 may be practicable.

[0045] A foamed solution of aerated cleaning liquid is discharged fromthe second mixing element 68 and directed toward the scrub head 20 viaconduit 110. Flow within conduit 110 is separated by a T coupling 112into conduits 114 and 116. The outlet of conduits 114, 116 are providedabove associated disk brushes 22. As illustrated in FIG. 4, flow fromconduits 114, 116 exits near the center of the scrub brushes 22 todeliver cleaning fluid into an annular trough 122 in the pad driver hub124. A series of holes 126 in the bottom of trough 122 pass the aeratedcleaning liquid down to the central region of the cleaning brush 22.During operation, the cleaning liquid is centrifuged out under the brush22 in contact with the hard floor surface. Alternative approaches toaerated cleaning liquid delivery would be appreciated by those skilledin the relevant arts.

[0046] A foam control switch 130 is electrically connected to the aircompressor 62, cleaning liquid pump 82, and solenoid valve 72 forcontrolling operation of the foam aerator system 60. The foam controlswitch 130 may include a manual switch mounted on the control panel.

[0047] In operation, electrical current flows to the air compressor 62,fluid pump 82, and electric solenoid valve 72. Pressurized air isdirected through conduit 78, check valve 76, and conduit 80. Pressurizedcleaning solution is directed through conduit 88, metering orifice 84,and conduit 90. Pressurized air and cleaning solution is received intothe first mixing element 66 and directed via conduit 92 through thecontrol valve 72, and then through conduit 100 and into the secondmixing element 68. As the mixture of air and cleaning solution flowsthrough the diffusion medium 108 of the second mixing element 68, foambubbles are generated. Foam output from the second mixing element 68 isdischarged via conduits 110, 114, 116 to the scrub brushes 22. In aparticular embodiment, the ratio of volumes between the unaeratedcleaning liquid and foamed cleaning liquid is approximately 1:8, e.g.,0.15 gallons of cleaning liquid is aerated to occupy 1.25 gallons. Othervolume ratios would yield acceptable scrubbing results. A foams“dryness” may be defined in relation to this volumetric expansion ratio.A “dry” foam having a higher expansion ratio as compared to a “wet”foam. High-expansion foams used in presently available types of carpetcleaning machines are actually relatively “dry” as the ratio of air towater is particularly high. Dry foams are used in carpet cleaning tofacilitate quick drying of the cleaned carpet. A “wet” foam is nottypically used in carpet cleaning devices as these foams can causeexcessive wetting of the carpet which may lead long drying times andmold development.

[0048] The cleaning machine 10 is then moved forward, with the foam-likeaerated cleaning liquid being dispensed from the conduits 114, 116 atthe front of the chassis. As the cleaning machine 10 moves forward, thebrushes 22 engage the aerated cleaning liquid and hard floor surface.The foamed cleaning liquid permits an efficient wetting of the hardfloor surface, even at dramatically reduced cleaning solution usage. Forexample, cleaning liquid rates of 0.2 gallons per minute have yieldedacceptable results. In comparison, prior art scrubbing machines ofsimilar size often utilize approximately 1 gallon per minute. Theprocess of mechanically working the foam with the brushes 22 results insubstantial defoaming or de-aeration (up to 95% reduction in volume) ofthe foamed cleaning solution prior to soiled solution recovery. Incontrast, prior art devices using known chemical detergents may createadditional foam by the brush action, necessitating defoaming devices asmentioned herein.

[0049] In operation, a soiled solution of cleaning liquid and soil isdeveloped by the interaction of the scrubbing medium in contact with thefoamed cleaning liquid and the hard floor surface. The soiled solutionincludes partially deaerated cleaning liquid and soil released from thehard floor surface. The soiled solution is recovered from the hard floorsurface through vacuum squeegee 34 and conveyed to the recovery tank 12through hose 36. Alternative soiled solution recovery devices may alsobe practicable. The recovered soiled solution may be treated to reducefoam via known defoaming techniques, including an addition of defoamingchemical to the recovery tank 12. In the embodiment described herein,the soiled solution is substantially defoamed during the scrubbingprocess. The above referenced particular surfactant beneficially yieldsa foamed cleaning solution which rapidly de-aerates after contact withthe rotating scrub brushes 22. As a result, in a preferred embodiment noadditional defoaming devices or chemicals are required.

[0050]FIG. 5 illustrates a scrubber utilizing an alternative soiledsolution recovery device 32. The soiled solution recovery device 32 mayinclude a non-vacuumized mechanical device for lifting the soiledsolution away from the floor surface and conveying the soiled solutiontoward a collection tank or receptacle 142. In the embodiment of FIG. 5the soiled solution recovery device includes a plurality of wipingmedium such as pliable material elements 140 which are rotated intocontact with the floor surface to engage and lift the soiled solutionfrom the floor surface. The pliable material elements 140 may be of anabsorbent material. The pliable material elements 140 convey thesolution to the collection receptacle 142. Solution captured on thepliable elements 140 may be removed via a mechanical action, such asthrough a shearing device or a squeezing device. In the embodiment ofFIG. 5, the mechanical action used to remove soiled solution from thepliable material elements 140 is a scraper bar 144 which engages thepliable material elements 140 to release the soiled solution.Alternative mechanical devices, structures, or systems may be used toconvey the soiled solution from the floor surface toward a collectionreceptacle.

[0051] The scrubber 10 may include a defoaming device or system toreduce the volume of the collected soiled solution. The defoaming deviceor system may be part of the soiled solution collection and handlingdevice 32 or may be disposed in relation to the soiled solution tank 12.The defoaming device or system may include a chemical defoaming systemfor applying a defoaming chemical to collected foam. The defoamingdevice may include an acoustic and/or mechanical defoaming device. FIG.6 illustrates one particular defoaming device 146 for use with thescrubber of FIGS. 1-4. FIG. 6 is a cross sectional view taken throughthe recovery tank 12, vacuum conduit 36, and vacuum squeegee 34. Thedefoaming device 146 may be an selective device finding applicability inhigh foam situations. Foam lifted from the squeegee 34 through vacuumconduit 36 is passed by the defoaming device 146 containing a defoamingchemical 148. The defoaming device 146 is a passive device allowing thechemical 148 to passively interact with the recovered foam. Thedefoaming device 146 may have a porous or apertured element forpromoting contact between the defoaming chemical or defoamant 148 andthe recovered foam. One particular defoamant which may be used isFOAM-OUT™ manufactured by LaPorte Water Technologies, Inc., ofAlpharetta, Ga. Alternative defoaming devices or defoamants may also bepracticable.

[0052] Another defoaming device is illustrated in FIG. 5 and FIG. 6 asnumeral 130. Defoaming device 130 is a radiant heating element disposedabove the soiled solution in the recovery tank 12. Radiant heatingelement 130 may be an electric heating element powered by the batteries46, or may be powered by another heat source, such as propane orrecovered heat from an IC engine. Radiant heating element 130 functionsto de-aerate foam within the solution tank 12 via a thermal process. Oneor more radiant heating elements 130 may be utilized in embodiments ofthe present invention.

[0053] Additional aspects of the present invention will be addressed.Regarding the foam system, alternative foam generation systems may bepracticable. In the above described embodiment, a compressed air andpressurized cleaning liquid process is utilized. Other means forgenerating the foam-like aerated cleaning liquid may utilize known foamgenerating devices. One or more known foam generating devices may beused to generate the foam-like aerated cleaning liquid for use in ascrubbing operation as described herein.

[0054] Foam generation devices utilizing an agitation process are known.An agitation process uses a mechanical device, such as a rotatingimpeller, to engage and entrain air within a solution. U.S. Pat. Nos.3,761,987 and 3,931,662 each disclose an agitation-type foam generator,the disclosures of which are incorporated by reference herein.

[0055] Foam generation devices utilizing a pressurized liquid processare also known. These devices include foam generating nozzles such asfor use in fire fighting equipment. Ambient air may be aspirated into asolution at the nozzle end of a hose by an air-aspirating nozzle.Aspirated foam systems do not use compressed gases to create the foam. Amixture of foam concentrate and water is pumped through a specialaspirating nozzle located at the end of the delivery hose. This specialnozzle is designed to draw in atmospheric air and mix it with the foamconcentrate-water mix to create foam.

[0056] Foam generation devices utilizing a pressurized gas process arealso known. A method of expanding the volume of a solution into foam isto introduce compressed air into the solution prior to the solutionreaching a nozzle. Compressed gas, usually air, is introduced into thefoam concentrate-water mixture at high pressure, usually in the range of60-100 psi. The air is mixed with the foam concentrate-water mixtureeither with an active mixing device or a passive mixing device which canbe as simple as a long length of conduit.

[0057] Referring to FIGS. 7 and 8, an additional chemical dispenseraspect of the present invention is disclosed. Illustrated as numeral150, a chemical dispenser may be utilized to combine water and thesurfactant to form the cleaning liquid. The term “dispenser” as usedherein is broadly meant to include devices or systems for providing,distributing, releasing, injecting, conveying, and/or dosing a chemicalor chemicals into a solution to create the cleaning liquid. A variety ofchemical dispensers would be appreciated by those skilled in therelevant arts. A chemical dispenser is particularly well suited for ascrubber according to the present invention given the relatively smallamount of surfactant needed to form an aerated cleaning liquid. Thechemical dispenser 150 may include active and/or passive elements. Apassive element chemical dispenser is illustrated in FIG. 7, wherein thesurfactant 152 is permitted to diffuse through a porous medium 154 andinto conduit 100. An active element chemical dispenser is illustrated inFIG. 8, wherein the surfactant 152 is pumped through one or moreconduits 156, 158, 160 for mixing with water. In one embodiment,chemical dispenser 150 may dispense the chemical to a water tank 162 viaconduit 156 for mixing with a predetermined volume of water, such asduring refilling. In another embodiment, chemical dispenser 150 maydispense the chemical via lines 158 and/or 160 for mixing within theassociated conduits to generate the cleaning liquid.

[0058] Yet another aspect of the chemical dispenser 150 is the provisionof a removable cartridge 164 containing the surfactant 152 and/or otherchemicals. The term “cartridge” as used herein is broadly meant toinclude structures for holding a chemical, including but not limited tosealed or unsealed tanks, bottles, vessels, and other containers. Thecartridge 164 may be specifically adapted to engage a retainingstructure 166 on the machine 10. A variety of cartridges 164 andretaining structures 166 would be appreciated by those skilled in therelevant arts. The chemical dispenser 150 may include one or moredisposable chemical cartridges 164. A family of chemical cartridges 164may be provided, each member of the family having a differentpredetermined surfactant and/or chemical contained therein. For example,a first chemical cartridge 164 may include a surfactant and otherchemicals (such as disinfectants, solvents, alkaline builders, etc.)specifically adapted for a heavily soiled surface, with a secondchemical cartridge 164 being adapted for lightly soiled surface.

[0059] Distribution of the aerated cleaning liquid may includealternative structures. For example, the aerated solution may be sprayedon the hard floor surface or brushes 22 or both. The aerated solutionmay be delivered through the brushes 22, such as via apertures in thebrush 22, and/or applied directly to the floor surface in front of thebrushes 22. Distribution of aerated cleaning liquid may include aselective application to the hard floor surface, the brushes, or both.Alternative distribution systems may be appreciated by those skilled inthe relevant art.

[0060] As various changes could be made in the above methods withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A method of cleaning a hard floor surface with a surface maintenancevehicle, said method comprising the steps of: generating a foam-likeaerated cleaning liquid; selectively conveying said foam-like aeratedcleaning liquid to the hard floor surface and a rotating scrubbingmedium operatively coupled to the surface maintenance vehicle; scrubbingthe hard floor surface with said rotating scrubbing medium and saidfoam-like aerated cleaning liquid so as to loosen soil from the hardfloor surface leaving behind a soiled solution of cleaning liquid andsoil; and removing at least a portion of the soiled solution from thehard floor surface through a fluid recovery device.
 2. A method of claim1 wherein the scrubbing medium is a disk-type scrub brush rotating abouta generally vertical axis of rotation relative to said hard floorsurface.
 3. A method of claim 1 wherein the scrubbing medium is acylindrical-type scrub brush rotating about a generally horizontal axisof rotation and generally transverse to an operating direction ofmovement of said surface maintenance vehicle.
 4. A method of claim 1wherein the step of generating the foam-like aerated cleaning liquid isselectively achieved by way of an air compression process, an agitationprocess, or both.
 5. A method of claim 1 wherein the step of generatingthe foam-like aerated cleaning liquid is achieved by way of a processutilizing compressed air and pressurized cleaning liquid.
 6. A method ofclaim 1 wherein the step of removing soiled solution from the hard floorsurface is achieved via a non-vacuum process.
 7. The method of claim 6wherein the non-vacuum process includes the steps of: physically wipingthe hard floor surface with a wiping medium; lifting soiled solutionaway from the hard floor surface; and depositing the soiled solution ina recovery tank.
 8. A method of claim 1 wherein the step of selectivelyconveying the foam-like aerated cleaning liquid to the hard floorsurface and the scrub brush includes the step of selectively applyingthe aerated cleaning liquid directly to the floor surface and directlyto the scrubbing medium.
 9. A method of claim 1 wherein the cleaningliquid is selected such that the foam-like aerated cleaning liquidsubstantially de-aerates on the hard floor surface prior to removal ofthe soiled solution.
 10. A method of claim 1 wherein the cleaning liquidis provided through a step of mixing water with a surfactant within asolution tank.
 11. A method of claim 1 wherein the cleaning liquid isprovided through a step of mixing water with a surfactant dispensed froma chemical dispenser.
 12. A method of claim 11 wherein the chemicaldispenser includes a removable cartridge element containing saidsurfactant.
 13. A method of claim 1 further comprising the step ofdefoaming soiled solution recovered by the fluid recovery device via achemical or thermal device.
 14. A method of cleaning a hard floorsurface comprising the steps of: generating a foam-like aerated cleaningliquid by mixing pressurized air with a cleaning liquid; selectivelyconveying said foam-like aerated cleaning liquid to the hard floorsurface and a scrubbing medium operatively coupled to the surfacemaintenance vehicle; scrubbing the hard floor surface with saidscrubbing medium and said foam-like aerated cleaning liquid so as toloosen soil from the hard floor surface leaving behind a soiled solutionof cleaning liquid and soil; and removing at least a portion of thesoiled solution from the hard floor surface through a fluid recoverydevice.
 15. A method of claim 14 wherein the step of scrubbing the hardfloor surface is achieved by rotating or oscillating the scrubbingmedium relative to the hard floor surface.
 16. A method of claim 14wherein the scrubbing medium is a disk-type scrub brush rotating about agenerally vertical axis of rotation relative to said hard floor surface.17. A method of claim 14 wherein the scrubbing medium is acylindrical-type scrub brush rotating about a generally horizontal axisof rotation and generally transverse to an operating direction ofmovement of said surface maintenance vehicle.
 18. A method of claim 14wherein the step of removing soiled solution from the hard floor surfaceis achieved via a non-vacuum process.
 19. The method of claim 18 whereinthe non-vacuum process includes the steps of: physically wiping the hardfloor surface with a wiping medium; lifting soiled solution away fromthe hard floor surface; and depositing the soiled solution in a recoverytank.
 20. A method of claim 14 wherein the step of selectively conveyingthe foam-like aerated cleaning liquid to the hard floor surface and thescrubbing medium includes the step of selectively applying the aeratedcleaning liquid directly to the floor surface and directly to thescrubbing medium.
 21. A method of claim 14 wherein the cleaning liquidis selected such that the foam-like aerated cleaning liquidsubstantially de-aerates on the hard floor surface prior to removal ofthe soiled solution.
 22. A method of claim 14 wherein the step ofgenerating the foam-like aerated cleaning liquid includes the step ofmixing pressurized air with pressurized cleaning liquid.
 23. A method ofclaim 22 wherein the step of mixing pressurized air with pressurizedcleaning liquid is achieved via one or more passive mixing elements. 24.A method of claim 14 wherein the cleaning liquid is provided through astep of mixing water with a surfactant within a solution tank.
 25. Amethod of claim 14 wherein the cleaning liquid is provided through astep of mixing water with a surfactant dispensed from a chemicaldispenser.
 26. A method of claim 25 wherein the chemical dispenserincludes a removable cartridge element containing said surfactant.
 27. Amethod of claim 14 further comprising the step of defoaming soiledsolution recovered by the fluid recovery device via a chemical orthermal device.
 28. A method of cleaning a hard floor surface comprisingthe steps of: generating a foam-like aerated cleaning liquid;selectively conveying said foam-like aerated cleaning liquid to the hardfloor surface and a scrubbing medium operatively coupled to the surfacemaintenance vehicle; scrubbing the hard floor surface with saidscrubbing medium and said foam-like aerated cleaning liquid so as toloosen soil from the hard floor surface leaving behind a soiled solutionof cleaning liquid and soil; and non-vacuumized transporting at least aportion of the soiled solution from the hard floor surface and into therecovery tank.
 29. A method of claim 28 wherein the step of generatingthe foam-like aerated cleaning liquid is selectively achieved by way ofan air compression process, an agitation process, or both.
 30. A methodof claim 28 wherein the step of generating the foam-like aeratedcleaning liquid is achieved by way of a process utilizing compressed airand pressurized cleaning liquid.
 31. A method of claim 28 wherein thestep of scrubbing the hard floor surface is achieved by rotating oroscillating the scrubbing medium relative to the hard floor surface. 32.A method of claim 28 wherein the scrubbing medium is a disk-type scrubbrush rotating about a generally vertical axis of rotation relative tosaid hard floor surface.
 33. A method of claim 28 wherein the scrubbingmedium is a cylindrical-type scrub brush rotating about a generallyhorizontal axis of rotation and generally transverse to an operatingdirection of movement of said surface maintenance vehicle.
 34. Themethod of claim 28 wherein the step of non-vacuumized transporting thesoiled solution includes the steps of: physically wiping the hard floorsurface with a wiping medium; lifting soiled solution away from the hardfloor surface; and depositing the soiled solution in a recovery tank.35. A method of claim 28 wherein the cleaning liquid is selected suchthat the foam-like aerated cleaning liquid substantially de-aerates onthe hard floor surface prior to removal.
 36. A method of claim 28wherein the cleaning liquid is provided through a step of mixing waterwith a surfactant within a solution tank.
 37. A method of claim 28wherein the cleaning liquid is provided through a step of mixing waterwith a surfactant dispensed from a chemical dispenser.
 38. A method ofclaim 37 wherein the chemical dispenser includes a removable cartridgeelement containing said surfactant.
 39. A method of claim 28 furthercomprising the step of defoaming soiled solution recovered by the fluidrecovery device via a chemical or thermal device.
 40. A movable devicefor a hard floor surface cleaning process comprising: an aerator influid communication with a cleaning liquid, said aerator generating afoam-like aerated cleaning liquid from the cleaning liquid; a fluidconveyor coupled to the aerator, said fluid conveyor transferring thefoam-like aerated cleaning liquid into contact with the hard floorsurface; a rotating scrub medium engaging the hard floor surface and thefoam-like aerated cleaning liquid to loosen soil from the hard floorsurface to leave behind a soiled solution of cleaning liquid and soil;and a fluid recovery device removing at least a portion of the soiledsolution from the hard floor surface.
 41. A device of claim 40 whereinthe cleaning liquid includes water and a surfactant.
 42. A device ofclaim 40 wherein the aerator includes a mixing element receivingpressurized cleaning liquid, pressurized air, or both.
 43. A device ofclaim 40 wherein the scrub medium is a disk-type scrub brush rotatingabout a generally vertical axis of rotation relative to the hard floorsurface.
 44. A device of claim 40 wherein the scrub medium is acylindrical-type scrub brush rotated about a generally horizontal axisof rotation relative to the hard floor surface.
 45. A device of claim 40wherein the cleaning liquid is selected such that the foam-like aeratedcleaning liquid substantially de-aerates on the hard floor surface priorto removal of the soiled solution.
 46. A device of claim 40 wherein thefluid recovery device is a vacuum device for conveying soiled solutionfrom the hard floor surface.
 47. A device of claim 40 wherein thecleaning liquid is water mixed with a chemical via a chemical dispenser.48. A device of claim 47 wherein the chemical dispenser includes aremovable chemical cartridge.
 49. A device of claim 40 wherein the fluidconveyer directs the aerated cleaning liquid through a conduit having adischarge outlet proximate to the center of the disk scrub brush.
 50. Adevice of claim 40 further comprising: a defoaming device forde-aerating foam recovered by the device.
 51. A device of claim 50wherein the defoaming device includes a device for dispensing a chemicaldefoamer.
 52. A device of claim 50 wherein the defoaming device is aradiant heating element provided in operative relation to recoveredfoam.
 53. A surface maintenance vehicle for a hard floor surfacecleaning process comprising: a tank holding water; a chemical dispenser,said dispenser delivering a chemical into water to form a cleaningliquid; an aerator generating an aerated cleaning liquid from thecleaning liquid; a fluid conveyor in fluid communication with theaerator, said fluid conveyor directing the aerated cleaning liquid intocontact with the hard floor surface; a scrub brush engaging the hardfloor surface and the aerated cleaning liquid to loosen soil from thehard floor surface to leave behind a soiled solution of cleaning liquidand soil; and a fluid recovery device removing at least a portion of thesoiled solution from the hard floor surface.
 54. A surface maintenancevehiclee of claim 53 wherein the chemical dispenser includes a removablecartridge containing a surfactant.
 55. A surface maintenance vehicle ofclaim 53 wherein the chemical dispenser dispenses the chemical into thetank.
 56. A surface maintenance vehicle of claim 53 wherein the chemicaldispenser dispenses the chemical into a conduit for mixing water withinthe conduit with the chemical.
 57. A surface maintenance vehicle ofclaim 53 further comprising a de-foaming device for reducing the volumeof recovered foam within a recovered solution tank, said defoamingdevice selected from a group including: a device for dispensing achemical defoamant and a radiant heating element.